Question

There are 25 rows of seats in an auditorium. The first row is of 20 seats, the second of 22 seats, the third of 24 seats, and so on. How many chairs are there in the 21st row ?​

Answer 1

Answer:

20 + 22 + 24 + .......... 25 terms

These are in AP

a = 20

n= 25

d = 2

nth term in AP Tn = a + (n-1)d

✓✓✓

nth term = 20 + (25-1)2 = 20+(24×2) = 20+48 = 68

✓✓✓✓✓ In 21st row there will be 68 seats ✓✓✓✓✓

Step-by-step explanation:

Answer 2

Answer:

chairs of the 21st row t₂₁ = 60 chairs

Step-by-step explanation: